Screw-cutting die



J. GRIFFITHLGEQ TING MACHINE.

SCREW CUT Ptented Jan. 18, 1853.

No.l 9,547.

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'UNITED STATES PATENT OFFICE'.

JOHN GRIFFITHS, OF lPHILADELPHIA, PENNSYLVANIA.

SCREW-CUTTING DIE.

Specification of Letters Patent No. 9,547, dated January 18, 1853.

'2 a longitudinal section taken longitudinally through the machine, Fig. 3 a plan of the dies, die seats, and their set-screws, and

the die stock, Fig. 4, a longitudinal elevation of the die, Fig. 5 a plan of the inner face of the die, Fig. 6 a longitudinal elevation of the die-seat and Fig. 7, a plan of the outer face of the die seat.

Similar letters refer to similar parts.

My machine consists of a turned shaft (a) which is contained in and neatly fitted to a hollow mandrel (b). This shaft is grooved longitudinally, (c) to correspond with a key immovably xed to the mandrel, which while allowing the shaft to be drawn in a longitudinal direct-ion, compels it to revolve wit-h the mandrel when power is applied to the driving pulleys This shaft is entirely independent and distinct from the hollow mandrel, in which it slides with great ease, the friction being exceedingly small.

To the outer extremity of the shaft, a screw collar (e) is keyed, which revolves in two semi-circular screw plates (f-g), the shaft being driven forward or drawn backward according to the direction in which it is turned. The upper of these screw-plates (f) is keyed to a cap (7L), and the lower to a bed (i), both of which move upon a common joint The pitch of these screws, (via-that of the shaft, and those of the plates) determines the pitch of the screw to be cut on the pipe or bolt (is).

The threads of the screw-plates are cut to correspond with the screw collar of the shaft in the following manner: An ordinary cylindrical die having the same pitch as the screw collar of the shaft is keyed to the extremity of the shaft, (after unkeying the screw collar therefrom); the cap and bed are then made to approximate by means of an elliptical piece (Z), which is moved by a lever with the hand, so as to encircle and press against the cylindrical die which being made to revolve with the shaft, cuts lthe threads in the screw plates. If a diiferent pitch of screw be required, the screw plates and the screw collar of the shaft are removed by raising the cap by .a lever (n) with the hand, and lowering the bed by moving the lever with the hand until the elliptical piece (l) is horizont-al, which will make a sufficient opening to allow the shaft to be drawn out without injury to the threads of the screws. The screw-plates and the screw collar of the shaft are then unkeyed and replaced by those of the desired pitch.

As the screw collar of the shaft rests in the lower screw plate, (which will insure the necessary feed motion to the shaft when it revolves) the upper screw plate may be dispensed with in cutting the screws on pipes or bolts, and is only used in cutting the threads of the screwplates when by being pressed down upon the cylindrical die keyed to the shaft, it prevents the shaft being forced up out of line when pressed against by the lower screw plate, thus making it certain that the threads of the screw plates will be cut perfectly true, upon which depends the perfection of the screw cut on the pipe or bolt.

To the inner extremity of the shaft a face plate (o) is attached, to which a die-stock (p) is screwed or bolted. This die-stock has three or more dove-tail grooves, in which are screwed dove-tail pieces (g), through which pass set-screws (r). These set-screws work in the seats (s) of the dies (t), and serve to move the dies and seats to or from the center of the die stock, according to the diameter of the pipe or bolt on which the screw is to be cut. Different sizes of pipes and bolts may thus be cut by the same die, instead of each having its own die, which is the case when all other dies are used. The outer faces of the seats are channeled or grooved to correspond with channels or grooves in thevfaces of the dies in contact with the seats, and which when forced together by screw nuts (u) working on bolts, effeotually prevent the dies turning on their axis when cutting, to which they would otherwise be liable.

The die is composed of a circular piece of steel in whose periphery parallel threads are cut, orthreads having no pitch which are turned of near the outer face of the die givstock without softening it.

ing it a draft by which the screw of the pipe or boltis made with one cut.v An offset (o) is cut in the periphery of the die extending its whole width, the junction of the vertical face of which with the periphery forming the cutting edge of the die or the part which is brought in Contact with the pipe or bolt on which the screw is to be cut. The die is sharpened by simply grinding the vertical lface of the offset, which will thus bring a new portion of the periphery in Contact with the pipe or bolt. This can be immediately done upon removing the die from the die These dies should be so set, that if the vertical faces of their offsets were continued7 they would Ameet at the center of the die stock as shown in Fig. 3.

yFemale screws may be cut by using la single die. of this die is that one of three inches diani- .eter once fitted up, will last about one hun- One of the peculiar advantages.

which is brought in Contact' with the pipe or bolt by meansof the hand wheels which prevents the pipe or bolt from turning while being cutby the dies. These pieces can be easily slid out of the grooves of the cross heads and changed according to the diameter of the pipe or bolt. The vertical frame is iirmly iiired to the lower or horizontal frame (6') by a hand screw nut (7). The vertical can be detached from the horizontal frame and moved by the hand to Aor from the dies, by unserewing the nut (f) which permits short pipes and bolts to be cut. The pipe or bolt' is brought in a line with the dies by the hand wheels, which will insure the screw being cut true. The supports g2/) Vin which the mandrel revolves are firmly liXed to the horizontal frame. y

What I claim as my invention and desire to secure by Letters Patent is:

The circular die with an offset which makes a cutting edge which is held in position by a bolt and screw nut, the threads which are cut in its periphery being parallel instead of having a running pitch, substan tially in the manner and for the purposes as hereinbefore described.

JOHN GRIFFITHS.`

lVitnesses HENRY SIMPSON, JOHN T. CLEMENS. 

